Nuclear Carriers Vs Nuclear Subs
The writer retired as Flag Officer Commanding-in-Chief of the Eastern Naval Command, Visakhapatnam
The US defence secretary Ashton Carter is expected to visit Visakhapatnam on June 3 and then New Delhi on June 4-5 to sign the 10-year Indo-US Enhanced Defence Framework Agreement, and convince India to accept an American design for the recently announced indigenous 65,000-ton aircraft carrier, along with the latest American EMALS (Electromagnetic Aircraft Launch System) and AAWS (Advanced Arrester Wire System), and operate the latest American carrier-borne F-35C jet fighters. {Is that right}
In April 2015, the media reported that the defence ministry had cleared various pending projects, including funding of an initial Rs 30 crore as “seed money” to commence project work on India’s next indigenous 65,000-ton aircraft carrier, to be named INS Vishal.
The Indian Navy currently operates non-nuclear-powered aircraft carriers, i.e. the 56-year-old, 28,0000-ton, steam-driven INS Viraat and the 43,000-ton, steam-driven INS Vikramaditya. At the same time, the gas-turbine-powered 37,000-ton INS Vikrant is under construction and is expected to join the Navy in 2018. The reasons stated for the new INS Vishal are valid, i.e. for an aircraft carrier to be viable, it needs to embark at least 36 fighter aircraft and another 12 helicopters, and this is possible only on carriers larger than 65,000 tons (INS Vikramaditya and INS Vikrant can each embark only 18 fighters and 12 helicopters).
A debate has now started about the need or otherwise of nuclear propulsion for the proposed INS Vishal. Nuclear power is expensive to acquire, maintain and needs highly trained personnel to operate. While nuclear power provides natural stealth to submarines by enabling them to remain totally submerged in the ocean depths for months, a nuclear-powered aircraft carrier is visible and detectable by electronic and satellite surveillance as it sails on the ocean surface. Additionally, while nuclear power provides long periods of propulsion without refuelling, American nuclear-powered aircraft carriers still need weekly replenishment at sea (from a non-nuclear replenishment ship) of aviation fuel, lubricants, air armaments etc, and the same replenishment ship, needs to refuel another eight more conventionally powered warships every three days (these warships protect the aircraft carrier against various enemy threats).
In 1954, the world’s first nuclear submarine, the American USS Nautilus, was commissioned. It operated on LEU (low enriched uranium, i.e. below 19 per cent enrichment), and this reactor fuel enabled the single reactor submarine to operate for two years before uranium refuelling, and provided a total of 200 days sailing at economic speed.
Reactor uranium fuelling is expensive and time consuming. To overcome this shortcoming, the Americans gradually increased the uranium enrichment to HEU (highly enriched uranium, i.e. 93 per cent enrichment) to enable present-day American nuclear submarines and nuclear-powered aircraft carriers to operate for 25 years, without reactor fuel change. India does not have this HEU propulsion technology yet.
Apart from nuclear or conventional propulsion, aircraft carriers are further subdivided into three categories.
The first is the CATOBAR (catapult assisted takeoff but arrested recovery). It is the most expensive and most capable (rapid aircraft launch rate of one aircraft every 20 seconds, while the other two carrier types can launch at one minute per aircraft). It uses one or more catapults to launch aircraft within a 150-metre deck length and arrester wires to recover the aircraft which land within a 100-metre deck length by using an aircraft tail hook to attach themselves to one of the three or four arrester wires.
Earlier, American aircraft carriers used steam catapults and hydraulic arrester wires, but now the latest 2015 American Ford class carrier will operate the new EMALS and AAWS. These two new systems, which are now on offer to the Indian Navy, require the aircraft carrier to produce three times more electric power than earlier CATOBAR designs. Ideally it would need two powerful nuclear reactors of the American A1B BECHTEL type, which power the new USS Gerald R. Ford, and each of which can produce 180 MWe. Unfortunately, the Americans are not willing to transfer nuclear reactor propulsion technology. As a result India will have a non-nuclear, gas-turbine -powered, but still very expensive INS Vishal.
The second type of carrier is the STOVL (short take-off and vertical landing) type that is the simplest and cheapest. INS Viraat is an example of STOVL, where the sub-sonic Sea Harrier jets take off (without catapult) in about 200 metres deck length from a ski jump ramp, and land vertically. The American supersonic F-35B is the latest stealth jet fighter capable of such short take-off and vertical landing operations.
The third type of carrier is the STOBAR (short take-off but arrested recovery), which is used on INS Vikramaditya (and also for the INS Vikrant under construction). Here the Russian MiG-29K or the Indian light combat aircraft takes off from 200 metres deck length (without catapult) from a ski jump ramp and lands in 100 metres deck length using its tail hook to catch one of three hydraulic arrester wires.
The UK has got nuclear reactor technology for its nuclear submarines, but has wisely decided that its next two 65,000-ton aircraft carriers (due for commissioning in 2018 and 2020) will be non-nuclear, STOVL type and conventionally powered by gas turbines. The aircraft selected are the American F-35B jets. These British carriers are estimated to cost about $4 billion each (the new American nuclear Ford class 100,000-ton carrier with EMALS and AAWS costs $13 billion).
Before India embarks on a new 65,000-ton aircraft carrier and its aircraft, it needs to look closely at funding availability (for aircraft, ship, spares, training etc), state of indigenous marine nuclear powered reactor technology, availability of indigenous uranium supplies (and whether our limited uranium stocks are better used for indigenous nuclear powered submarines), and, finally, vulnerability of the aircraft carrier to Chinese nuclear submarines and the new-shore-based 1,500-km-range DF-21D, anti-aircraft carrier ballistic missile system which may be based on Pakistan’s coast. The aircraft would need to be a fifth-generation stealth fighter like the American F-35B (STOVL) or a modified version of the Russian FGFA (STOBAR) planned for the Indian Air Force. To put it simply, India could build two STOVL or two STOBAR non-nuclear carriers for the cost of one nuclear CATOBAR carrier. The money saved could be gainfully used for indigenous production of critically needed nuclear and conventional submarines
